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Fix performance regression in Model.objects.all().delete()

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Avoid generating unnecessary subquery for full table deletes to restore fast deletes and compatibility with MySQL LOCK TABLES.
References #660
This commit is contained in:
utkarsh.arya@zomato.com 2025-11-15 22:58:55 +00:00
parent 437196da9a
commit 368e074192
2 changed files with 9 additions and 0 deletions
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2
django/db/models/sql/compiler.py
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@ -1407,6 +1407,8 @@ class SQLInsertCompiler(SQLCompiler):
class SQLDeleteCompiler(SQLCompiler): class SQLDeleteCompiler(SQLCompiler):
@cached_property @cached_property
def single_alias(self): def single_alias(self):
# Ensure base table is in aliases.
self.query.get_initial_alias()
return sum(self.query.alias_refcount[t] > 0 for t in self.query.alias_map) == 1 return sum(self.query.alias_refcount[t] > 0 for t in self.query.alias_map) == 1
def _as_sql(self, query): def _as_sql(self, query):

7
tests/delete/tests.py
View file

@ -606,6 +606,13 @@ class DeletionTests(TestCase):
class FastDeleteTests(TestCase): class FastDeleteTests(TestCase):
def test_fast_delete_all(self):
with self.assertNumQueries(1) as ctx:
User.objects.all().delete()
sql = ctx.captured_queries[0]['sql']
# No subqueries is used when performing a full delete.
self.assertNotIn('SELECT', sql)
def test_fast_delete_fk(self): def test_fast_delete_fk(self):
u = User.objects.create( u = User.objects.create(
avatar=Avatar.objects.create() avatar=Avatar.objects.create()